1. Field of the Invention
The present invention relates to a method for determining abnormality of a temperature sensor used in an image forming apparatus and the image forming apparatus using the same.
2. Description of the Related Art
Conventionally, the image forming apparatus performs fixing at a predetermined temperature so that toner is controlled to form an image on a sheet, and controls a fixing lamp by detecting the temperature of a temperature sensor of a fixing apparatus. The abnormality or failure of the fitting of a temperature sensor may lead to an error of the detected temperature, as a result, a fire, or even damage to the machine may be caused.
Accordingly, as a usual method for detecting whether the temperature sensor is normal or not, it is determined whether the temperature variation amount of the fixing apparatus in a predetermined time period reaches a predetermined reference temperature variation amount or not. If the risen temperature variation amount in a predetermined time period is less than the predetermined reference temperature variation amount, it is determined that the temperature sensor is abnormal.
However, the risen temperature variation amount in a predetermined time period may also be less than the predetermined reference temperature variation amount, when an input voltage is less than a predetermined voltage. So that, in this case, it may be determined that the temperature sensor is abnormal because of instability of the input voltage, even though the temperature sensor is normal.